Add retry

README.md

@@ -84,6 +84,19 @@ You can similarly auto-capture exceptions using `resultify(...)`. Please note th
 Err(TypeError())
 ```
 
+
+You can `retry` a function that returns a `Result` type with a constant backoff.
+
+```
+>>> from resultify import resultify, retry
+... @retry(retries=2, delay=2, initial_delay=1):
+... @resultify(Exception)
+... def foo():
+...     # do something that needs retrying here
+```
+
+This example waits 1 second before executing the initial call, then attempts the initial call, then executes two retries, spaces out two seconds from the previous call. If any execution was a success, the `Ok` value will be returned. If the retries were exhausted and no `Ok` was returned, we return the `Err` value.
+
 Since documentation always lies, please refer to the unit tests for examples of usage.
 
 

resultify/__init__.py

@@ -1,3 +1,4 @@
+from time import sleep
 from functools import wraps
 from typing import Any, Generic, TypeVar, Union, Type, Callable
 
@@ -113,3 +114,25 @@ def inner(*args, **kwargs):
         return inner
 
     return decorator
+
+
+def retry(retries: int = 0, delay: int = 0, initial_delay: int = 0):
+    def decorator(
+        function: Callable[..., Union[Ok[T], Err[E]]]
+    ) -> Callable[..., Union[Ok[T], Err[E]]]:
+        @wraps(function)
+        def func_with_retries(*args, **kwargs) -> Union[Ok[T], Err[E]]:
+            sleep(initial_delay)
+            _retries = retries
+            res: Union[Ok[T], Err[E]] = function(*args, **kwargs)
+            while _retries >= 1:
+                if res.is_ok():
+                    break
+                sleep(delay)
+                _retries -= 1
+                res = function(*args, **kwargs)
+            return res
+
+        return func_with_retries
+
+    return decorator

test/test_resultify.py

@@ -2,7 +2,7 @@
 
 import pytest
 
-from resultify import Err, Ok, UnwrapError, resultify
+from resultify import Err, Ok, UnwrapError, resultify, retry
 
 
 class TestOk:
@@ -124,3 +124,50 @@ def test_isinstance_result_type(self):
         n = Err("nay")
         assert isinstance(o, (Ok, Err))
         assert isinstance(n, (Ok, Err))
+
+
+class TestRetry:
+    def test_retry_fail(self):
+        class Config:
+            value = "asdfasdfasdf"
+            counter = 0
+            failing_tries = 999
+            retries = 2
+
+        config = Config()
+
+        @retry(retries=config.retries)
+        @resultify(Exception)
+        def foo():
+            config.counter += 1
+            if config.counter <= config.failing_tries:
+                raise TypeError()
+            else:
+                return config.value
+
+        x = foo()
+        assert isinstance(x, Err)
+        assert config.counter == 3
+
+    def test_retry_ok(self):
+        class Config:
+            value = "asdfasdfasdf"
+            counter = 0
+            failing_tries = 2
+            retries = 2
+
+        config = Config()
+
+        @retry(retries=config.retries)
+        @resultify(Exception)
+        def foo():
+            config.counter += 1
+            if config.counter <= config.failing_tries:
+                raise TypeError()
+            else:
+                return config.value
+
+        x = foo()
+        assert isinstance(x, Ok)
+        assert x.ok() == config.value
+        assert config.counter == 3